Another piece of economic data released Monday points to the jobs report issued Friday as the outlier on the labor market.

The Conference Board’s employment trends index rose to 115.76 in December from an upwardly revised 115.72, representing a 5.2% gain from the year-earlier period. While that’s just a gain of 0.03% on a monthly basis, it’s the fifth increase in six months for the index that aggregates eight different labor-market indicators.

In a phone conversation with MarketWatch, The Conference Board’s Gad Levanon, who’s director of macroeconomic research, said the six- and 12-month direction of the employment trends index points to solid jobs growth ahead.

Asked specifically about the Labor Department’s data showing 74,000 jobs created, Levanon said he doesn’t know whether the December figures will be heavily revised but expects better readings for January and February.

“It’s probably below trend. I don’t know how much it will be revised, but the [data] should be higher in January and February,” he says.

He says the most interesting development in the labor market is the rapid decline in the unemployment rate, now down to 6.7%. “According to the [Congressional Budget Office], full employment is around 5.5%. While we discuss the weakness of the labor market, we’ll be close to a period of full employment.”

Levanon says what’s likely happening is the retirement of the baby boomers is pressuring the participation rate. Even data showing an increasing participation for those 55 and older should be broken up into those aged 55 to 65, and those 65 and over. The reason the 55-and-over participation rate is increasing is in part a composition element as well as a need to work longer for those who lost money due to the bursting of the housing and to a lesser extent stock market during the Great Recession.

He also commented on data showing weak productivity. Federal Reserve Chairman Ben Bernanke has suggested that the labor market has benefited from companies not investing in boosting their productivity. “It could be that the trend in productivity has slowed down. Another [factor] is that wages are so weak that, on the margin, when companies are deciding whether to add more people or add equipment, they choose to hire more people.”